Golf ball covers and mantles comprising glass particles

ABSTRACT

Disclosed herein is a golf ball with a mantle or cover layer formed from a composition comprising glass particles. More specifically, the golfball has a mantle and/or cover that contains a combination of glass particles and an ionomeric component or a non-ionomeric component.

CROSS REFERENCES TO RELATED APPLICATIONS

The Present application is a continuation of a U.S. patent applicationSer. No. 11/687,550, filed on Mar. 16, 2007, which is a continuationapplication of U.S. patent application Ser. No. 11/147,866, filed onJun. 7, 2005, now U.S. Pat. No. 7,192,368.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to golf ball covers and mantles comprisingglass particles, preferably surface treated glass particles.

2. Description of the Related Art

Modern golf balls typically employ ionomeric resins or polyurethanes ascover materials. Ionomeric resins, as a result of their toughness,durability, and wide range of hardness values, have become materials ofchoice for golf ball covers over traditional rubbers. Ionomeric resinsgenerally comprise an alpha-olefin and an alpha, beta-ethylenicallyunsaturated mono- or dicarboxylic acid neutralized with metal ions tothe extent desired. Olefins which have been employed to prepareionomeric resins include ethylene, propylene, butene-1 and the like.Unsaturated carboxylic acids which have been employed to prepareionomeric resins include acrylic, methacrylic, ethacrylic,o-chloroacrylic, crotonic, maleic, fumaric, itaconic and the like.Ionomeric resins include copolymers of ethylene with acrylic acid suchas those sold by Exxon Corporation under the trademark “IOTEK”, as wellas copolymers of ethylene with methacrylic acid such as those sold byE.I. DuPont Nemours & Company under the trademark “SURLYN”. In someinstances, a softening comonomer such as an acrylate ester has beenincluded such that the ionomeric copolymer is an ionomeric terpolymer.Although various compositions have been employed to provide golf ballsof varying playability characteristics, a need continues forcompositions and covers which can be employed to provide golf balls thatexhibit good playability and durability.

There are no commercially available golf balls that are generally knownto contain surface treated glass particles or materials. The glassparticles may be used in a golf ball cover or cover layers, in themantle, or both, to reinforce the golf ball cover layer(s) and/or mantlelayer. U.S. Pat. No. 6,193,617 discloses golf balls with an outer covercomprising hard particles such as diamond particles, and a predeterminednumber of the hard particles protrude from the outer surface of theouter cover. However, there is no indication in the patent that surfacetreated glass particles can be used in a golf ball cover or mantlelayer.

In view of known strength and durability properties of glass and glassparticles, it would be desirable to utilize glass particles in theconstruction of a golf ball. Specifically, it would be desirable to usesurface treated glass particles in a golf ball cover and/or mantlelayer. There is a particular need for improved golf ball cover andmantle materials, particularly golf balls with increased compression andcoefficient of restitution as well as improved durability with the sameor higher coefficient of restitution.

BRIEF SUMMARY OF THE INVENTION

An object of the invention is to provide a highly durable golf ball.Another object of the invention is to provide a golf ball with a coveror mantle layer comprising surface treated glass particles.

A further object of the invention is to provide a golfball wherein thecoefficient of restitution and compression is maintained or increased.

Other objects of the invention will be in part obvious and in partpointed out more in detail hereinafter.

A preferred embodiment is a golf ball having a core and at least onecover layer disposed about said core. The cover layer includes surfacetreated glass particles.

Another preferred embodiment is a golf ball having a cover and a corecentrally disposed within said cover. The cover includes a combinationof at least a first component and a second component. The firstcomponent comprises surface treated glass particles. The secondcomponent comprises an ionomer or blend of ionomers, a non-ionomer orblend of non-ionomers, or a blend of ionomer and non-ionomer.Preferably, the golf ball has a coefficient of restitution of at least0.770.

Having briefly described the present invention, the above and furtherobjects, features and advantages thereof will be recognized by thoseskilled in the pertinent art from the following detailed description ofthe invention when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 shows a cross-sectional view of a golf ball with a covercomprising surface treated glass particles.

FIG. 2 shows a multi-layered ball with a cover comprising surfacetreated glass particles.

DETAILED DESCRIPTION OF THE INVENTION

The invention in a preferred form is a golf ball having at least onecover layer with a resin composition comprising a combination of surfacetreated glass particles and an ionomeric or non-ionomeric component, thecontent of the glass particles being from about 0.5 to about 40 weightpercent, preferably from about 1 to about 15 weight percent, and morepreferably from about 2 to about 10 weight percent of the resincomposition, the golfball having a coefficient of restitution of atleast 0.770. The glass particles are preferably surface treated with asilane, such as, for example, vinylsilane, acrylsilane, aminosilane,epoxysilane or a combination thereof, although any other treatment knownin the art may be utilized if desired. The glass particles may beflakes, fibers or micro-particles. These particles may also be coatedwith a metal coating that is, for example, deposited by vacuummetallization or sputtering. Glass flakes preferably have a thickness ofabout 5±2 microns and a width of about 10 to about 4000 microns, andglass fibers preferably have a diameter of about 13 microns or less, anda length of about 35 to about 70 microns. Other glass particles, such asnanoparticles of less than one micron may also be used in addition tothe glass particles previously described.

An alternative form of the present invention golf ball comprises agolfball having a core, a mantle layer and at least one cover layerwherein the mantle layer comprises glass particles. The cover layer orlayers may also comprise glass particles.

The ionomeric component of the invention preferably is a copolymerformed from an alpha-olefin having 2 to 8 carbon atoms and an acid whichis selected from the group consisting of alpha, beta-ethylenicallyunsaturated mono- or dicarboxylic acids and is neutralized with cationswhich include at least one member selected from the group consisting ofzinc, lithium, sodium, manganese, calcium, chromium, nickel, aluminum,potassium, barium, tin, copper, and magnesium ions. Preferred cationsare zinc, sodium, lithium, and magnesium, and combinations thereof. Inone preferred embodiment, the copolymer is further formed from anunsaturated monomer of the acrylate ester class having from 3 to 21carbon atoms.

The non-ionomeric resin may be any non-ionomeric material known in theart, as further described herein.

The present invention relates to golf balls which employ constructionscontaining glass particles, preferably in the mantle and/or inner and/orouter cover compositions of golf balls having a core and one, two, ormore cover layers formed thereon. Some non-limiting examples ofcompositions according to the invention are as follows:

(1) mixture of glass particles and an ionomeric resin;

(2) mixture of glass particles and a terpolymer;

(3) mixture of glass particles and at least one non-ionomeric resin;

(4) mixture of glass particles and at least one non-ionomeric resin andat least one ionomeric resin;

(5) mixtures of glass particles and a thermoplastic or thermosetpolyurethane;

(6) mixtures of glass particles and a reaction injection polyurethane,polyurethane/polyurea or a polyurea.

The golfballs of the invention preferably have a coefficient ofrestitution of at least 0.770 and PGA compression of at least 60,preferably at least 80.

An “ionomeric copolymer” as this term is used herein is a copolymer ofan alpha-olefin and an alpha, beta-ethylenically unsaturated mono- ordicarboxylic acid with at least 3% of the carboxylic acid groups beingneutralized with metal ions. The alpha-olefin preferably has 2 to 8carbon atoms, the carboxylic acid preferably is acrylic acid,methacrylic acid, maleic acid, or the like and the metal ions include atleast one cation selected from the group consisting of ions of zinc,magnesium, lithium, barium, potassium, calcium, manganese, nickel,chromium, tin, aluminum, sodium, copper, or the like. Preferably thecation is zinc, sodium, lithium, or magnesium, or a combination thereof.The term “copolymer” includes (1) copolymers having two types ofmonomers which are polymerized together, (2) terpolymers (which areformed by the polymerization of three types of monomers), and (3)copolymers which are formed by the polymerization of more than threetypes of monomers.

An “ionomeric component”, as used herein, is an ionomeric copolymerwhich does not contain glass particles and which is capable of beingmixed or blended with the glass particles.

A “polyurethane”, as used herein, is any type of polyurethane and/orpolyurethane/polyurea material, such as a thermoplastic polyurethane, acast polyurethane, a reaction injection molded polyurethane, and thelike.

In a first embodiment, golfballs of the invention employ, preferably asa mantle layer and/or cover layer, a composition that is a mixture ofglass particles and an ionomeric resin or blend of ionomeric resins. Theglass particles are preferably surface treated with a silane couplingagent. The glass particles preferably comprise about 0.5 to about 40weight percent of the mixture, and the ionomeric copolymer is about 60to about 99.5 weight percent of the mixture.

Glass particles, such as glass flakes, have been used with a variety ofmaterials to improve properties such as dimensional stability, impactstrength, chemical resistance, wear resistance, and surface finish, andto reduce warpage and water/fluid absorption. Examples of commerciallyavailable glass particles are Microglas® Glass Flake and MicroglasFleka®, available from Nippon Glass Fiber Co. Ltd, Canada, and crushedand powdered Corning glass available from Elan Technology, Midway Ga.Other possible benefits, particularly when used in a mantle and/or coverlayer of a golfball include, but are not limited to, improveddurability; higher or harder compression; improved barrier properties;reduced water or moisture permeability; and higher toughness.

Ionomeric copolymers which may be used in the mixture include ionomericcopolymers of an alpha olefin of the formula RCH═CH₂ where R is H oralkyl radicals having 1 to 8 carbons, and an alpha, beta-ethylenicallyunsaturated carboxylic acid having from 3 to 8 carbons. The ionomericcopolymer has at least about 10 weight percent of the COOH groupsneutralized with metal cations, preferably zinc, sodium, lithium,magnesium, and the like.

Olefin/carboxylic acid copolymer ionomers which may be employed includethose wherein the carboxylic acid groups of the copolymer ionomer arepartially (for example, approximately 5 to 80 percent) neutralized bymetal ions such as but not limited to lithium, sodium, zinc andmagnesium, preferably zinc and sodium. Ionic copolymers may be zincneutralized ethylene/methacrylic acid ionomer copolymer, sodiumneutralized ethylene/acrylic acid copolymer ionomers, and mixturesthereof. The zinc neutralized ethylene/acrylic acid copolymer ionomercan be the reaction product of zinc neutralization of anethylene/acrylic acid copolymer having about 15 to 20 weight percentacrylic acid and a melt index of about 37 to about 100. These copolymerionomers usually have a relatively high molecular weight (for example, amelt index of about 0.1 to 1000 g/10 min., and/or a weight averagemolecular weight of 5000 up to one million). Useful copolymer ionomersinclude, for example, ethylene/acrylic acid copolymer ionomers sold byExxon Chemical Co. under the designation “IOTEK®” such as IOTEK® 7030,IOTEK® 7020, IOTEK® 7010, IOTEK® 8030, IOTEK® 8020, and IOTEK® 8000.Non-limiting examples of preferred IOTEK® copolymer ionomers for use inthe invention include IOTEK® 7010, IOTEK® 7030 and IOTEK® 8000.

In another embodiment, golf balls of the invention employ preferably asa cover, a composition that includes a mixture of a copolymer ofpolyphenylene oxide and polypropylene and a terpolymer. Terpolymerswhich may be employed include olefin/alkyl acrylate/carboxylic acidterpolymers or olefin/alkyl (meth)acrylate/carboxylic acid terpolymers.Typically, the carboxylic acid groups of the terpolymer ionomer arepartially (for example, approximately 5 to 80 percent) neutralized bymetal ions such as lithium, sodium, zinc, manganese, nickel, barium,tin, calcium, magnesium, copper and the like, preferably zinc, sodium,lithium, or magnesium, or a combination thereof, most preferably zinc orlithium or a combination thereof. These terpolymer ionomers usually havea relatively high molecular weight, e.g., a melt index of about 0.1 to1000 g/10 min., and/or a weight average molecular weight of 5000 up toone million. These terpolymers typically have about 50 to 98 weightpercent olefin, about 1 to 30 weight percent alkyl acrylate, and about 1to 20 weight percent carboxylic acid. The olefin may be any of ethylene,propylene, butene-1, hexene-1 and the like, preferably ethylene. Thealkyl (meth)acrylate may be any of methyl acrylate, methyl methacrylate,ethyl acrylate, ethyl methacrylate, butyl acrylate, butyl methacrylate,butyl vinyl ether, methyl vinyl ether, and the like, preferably methylacrylate. The carboxylic acid may be any one of acrylic acid,methacrylic acid, maleic acid, and fumaric acid. Monoesters of diacidssuch as methyl hydrogen maleate, methyl hydrogen fumarate, ethylhydrogen fumarate, and maleic anhydride which is considered to be acarboxylic acid may also be used. Preferably, the carboxylic acid isacrylic acid. Useful ethylene/methyl acrylate/acrylic acid terpolymersmay comprise about 50 to 98 weight percent, preferably about 65 to 85weight percent, most preferably about 76 weight percent ethylene, about1 to 30 weight percent, preferably 15 to 20 weight percent, mostpreferably about 18 weight percent methyl acrylate, and about 1 to 20weight percent, preferably about 4 to 10 weight percent, most preferablyabout 6 weight percent acrylic acid.

Olefin/alkyl (meth)acrylate/carboxylic acid terpolymers which arepreferred for use in the compositions employed in the invention areethylene/methyl acrylate/acrylic acid terpolymers such as those marketedby Exxon Chemical Co. under the name ESCOR®. Examples of theseterpolymers include ESCOR® ATX 320 and ESCOR® ATX 325.

Other olefin/alkyl (meth)acrylate/carboxylic acid terpolymers which maybe employed in the compositions employed in the invention include butare not limited to: ethylene/n-butyl acrylate/acrylic acid,ethylene/n-butyl acrylate/methacrylic acid, ethylene/2-ethoxyethylacrylate/acrylic acid, ethylene/2-ethoxyethyl acrylate/methacrylic acid,ethylene/n-pentyl acrylate/acrylic acid, ethylene/n-pentylacrylate/methacrylic acid, ethylene/n-octyl acrylate/acrylic acid,ethylene/2-ethyhexyl acrylate/acrylic acid, ethylene/n-propylacrylate/acrylic acid, ethylene/n-propyl acrylate/methacrylic acid,ethylene/n-heptyl acrylate/acrylic acid, ethylene/2-methoxylethylacrylate/acrylic acid, ethylene/3-methoxypropyl acrylate/acrylic acid,ethylene/3-ethoxypropyl acrylate/acrylic acid, andethylene/acrylate/acrylic acid. Compositions which may be employed toprovide golf balls according to this embodiment of the invention includeabout 0.5 to about 25 weight percent glass particles and about 75 weightpercent to about 95 weight percent terpolymer or blend of terpolymers.

Other useful terpolymer ionomers include, for example, ethylene/methylacrylate/acrylic acid terpolymer ionomers sold by Exxon Chemical Co.under the designation “IOTEK®”. Preferred terpolymer ionomers for use inthe invention include zinc neutralized ethylene/methyl acrylate/acrylicacid terpolymer ionomers such as IOTEK® 7520 and IOTEK® 7510.

Other terpolymer ionomers which may be used in the compositions employedin this embodiment of the invention include terpolymer ionomers such asthose disclosed in U.S. Pat. No. 4,690,981, the teachings of which areincorporated by reference in its entirety herein, and which areavailable from DuPont Corp. under the trade name SURLYN®.

In another embodiment, golf balls of the invention employ, preferably asa mantle or cover layer, compositions which include a mixture of glassparticles and at least one non-ionomeric resin. Examples ofnon-ionomeric resins suitable for use in the present invention include anon-ionomeric thermoplastic or thermosetting material such as, but notlimited to, a metallocene catalyzed polyolefin such as EXACT® materialavailable from EXXON and ENGAGE® material available from Dow Chem. Co.,a thermoplastic or thermoset polyurethane such TEXIN® thermoplasticpolyurethanes from Bayer Co. and the PELLATHANE® thermoplasticpolyurethanes from Dow Chemical Co., ionomer/rubber blends such as thosein U.S. Pat. Nos. 4,986,545; 5,098,105 and 5,187,013, thermoplasticblock polyesters, e.g., a polyester elastomer such as that marketed byDuPont under the trademark HYTREL®, thermoplastic block polyamides, suchas a polyether amide such as that marketed by Elf Atochem S. A. underthe trademark PEBAX®, acrylate copolymers such a those marketed byDuPont under the trademark ELVALOY® AC, a polyamide (blend of nylon andionomer) such as that marketed by Allied Signal Plastics under thetrademark CAPRON®, a Nylon 66 modified molding compound containingionomer such as that marketed by DuPont under the trademark ZYTEL® 408,a polycarbonate such as that marketed by General Electric under thetrademark LEXAN®, styrene-butadiene-styrene block copolymers, includingfunctionalized styrene-butadiene-styrene block copolymers,styrene-ethylene-butadiene-styrene (SEBS) block copolymers such asKRATON® materials from Shell Chem. Co., including functionalized SEBSblock copolymers, or a blend of two or more non-ionomeric thermoplasticor thermosetting materials. The composition may also include anionomeric resin or a terpolymer, in addition to the non-ionomeric resin.

Polyurethanes may also be used in the mantle and/or cover compositionswith the glass flakes. Polyurethanes are polymers which are used to forma broad range of products. They are generally formed by mixing twoprimary ingredients during processing. For the most commonly usedpolyurethanes, the two primary ingredients are a polyisocyanate (forexample, diphenyl methane diisocyanate monomer (“MDI”), hexamethylenediisocyanate (“HDI”) and toluene diisocyanate (“TDI”) and theirderivatives) and a polyol (for example, a polyester polyol or apolyether polyol). Any suitable polyurethane material may be used,depending on the properties desired.

A wide range of combinations of polyisocyanates and polyols, as well asother ingredients, are available. Furthermore, the end-use properties ofpolyurethanes can be controlled by the type of polyurethane utilized,for example, whether the material is thermoset (crosslinked molecularstructure) or thermoplastic (linear molecular structure).

Crosslinking occurs between the isocyanate groups (—NCO) and thepolyol's hydroxyl end-groups (—OH). Additionally, the end-usecharacteristics of polyurethanes can also be controlled by differenttypes of reactive chemicals and processing parameters. For example,catalysts are utilized to control polymerization rates. Depending uponthe processing method, reaction rates can be very quick (as in the casefor some reaction injection molding systems (“RIM”) or may be on theorder of several hours or longer (as in several coating systems).Consequently, a great variety of polyurethanes are suitable fordifferent end-users. A non-limiting example of a suitable polyurethaneis ESTANE® polyurethane commercially available from Noveon, Inc.

The physical properties of thermoset polyurethanes are controlledsubstantially by the degree of crosslinking. Tightly crosslinkedpolyurethanes are fairly rigid and strong. A lower amount ofcrosslinking results in materials that are flexible and resilient.Thermoplastic polyurethanes have some crosslinking, but purely byphysical means. The crosslinking bonds can be reversibly broken byincreasing temperature, as occurs during molding or extrusion. In thisregard, thermoplastic polyurethanes can be injection molded, andextruded as sheet and blow film. They can be used up to about 350° F.and are available in a wide range of hardnesses.

Polyurethane materials suitable for the present invention are formed bythe reaction of a polyisocyanate, a polyol, and optionally one or morechain extending diols. The polyisocyanate is selected from the groupincluding diphenyl methane diisocyanate (“MDI”); toluene diisocyanate(“TDI”); xylene diisocyanate (“XDI”); methylene bis-(4-cyclohexylisocyanate) (“HMDI”); hexamethylene diisocyanate (“HDI”); andnaphthalene-1,5,-diisocyanate (“NDI”).

One polyurethane component which can be used in the present inventionincorporates TMXDI (“META”) aliphatic isocyanate (Cytec Industries, WestPaterson, N.J.). Polyurethanes based on meta-tetramethylxylylenediisocyanate can provide improved gloss retention UV light stability,thermal stability, and hydrolytic stability. Additionally, TMXDIaliphatic isocyanate has demonstrated favorable toxicologicalproperties. Furthermore, because it has a low viscosity, it is usablewith a wider range of diols (to polyurethane) and diamines (topolyureas). If TMXDI is used, it typically, but not necessarily, isadded as a direct replacement for some or all of the other aliphaticisocyanates in accordance with the suggestions of the supplier. Becauseof slow reactivity of TMXDI, it may be useful or necessary to usecatalysts to have practical demolding times. Hardness, tensile strengthand elongation can be adjusted by adding further materials in accordancewith the supplier's instructions.

Further examples of suitable polyurethanes include polyurethane systemsformed via reaction injection molding (RIM). RIM processing to formvarious layers of a golf ball is described in detail in U.S. Pat. No.6,290,614, incorporated herein by reference.

Non-limiting examples of suitable RIM systems for use in the presentinvention are BAYFLEX® elastomeric polyurethane RIM systems, BAYDUR® GSsolid polyurethane RIM systems, PRISM® solid polyurethane RIM systems,all from Bayer Corporation (Pittsburgh, Pa.), SPECTRIM® reactionmoldable polyurethane and polyurea systems from Dow Chemical USA(Midland, Mich.), including SPECTRIM® MM 373-A (isocyanate) and 373-B(polyol), ELASTOLIT® SR systems from BASF® (Parsippany, N.J.), andVIBRARIM® systems from Uniroyal Corporation. Further preferred examplesare polyols, polyamines and isocyanates formed by processes forrecycling polyurethanes and polyureas. Peroxides, such as MEK-peroxideand dicumyl peroxide can be used. Furthermore, catalysts or activators,such as for example, cobalt octoate 6% can be used.

Moreover, in alternative embodiments, the mantle or cover layerformulation may also comprise a soft, low modulus non-ionomericthermoplastic elastomer including a polyester polyurethane such asESTANE® polyester polyurethane, commercially available from Noveon, Inc.

Two or more ionomers may be preblended prior to blending with the glassparticles, or they may all be blended together, to provide compositionsthat may be used in the invention, depending on the properties desired.Thus, preblends of hard and soft copolymer ionomers, as well aspreblends of high carboxylic acid copolymer ionomers and low carboxylicacid copolymer ionomers may be utilized to provide compositions for usein the invention. An example of such a preblend is a mixture of IOTEK®8000 and IOTEK® 7010.

Two or more terpolymers may be preblended prior to blending with any ofPPO/PP copolymer to provide compositions that may be used in theinvention. Thus, preblends of hard and soft terpolymers, as well aspreblends of high carboxylic acid terpolymers and low carboxylic acidterpolymers may be utilized to provide compositions for use in theinvention.

Referring now to the drawings, and first to FIG. 1, a golf ball 10including a core 12 and a cover 14 comprising glass particles is shown.

FIG. 2 shows a multi-layered golf ball 20 having a core 22, anintermediate layer (or mantle layer) 24, and a cover 26, wherein atleast one of the mantle or cover layers comprises glass particles.

Although the compositions employed in the invention may be used ingolfball construction including solid cores, one-piece balls and covers,these compositions are preferably employed as mantle and/or coverlayers. Golf ball mantle and cover layers can be produced by any methodknown in the art, such as injection molding, reaction injection moldingor compression molding the compositions containing glass particlesemployed herein over a wound or solid molded core, or a liquid core toproduce a golf ball having a diameter of about 1.680 inches or greaterand weighing about 1.620 ounces. In golf balls comprising multi-layeredcovers, any of the mantle and/or cover layers may comprise the glassparticle containing compositions employed herein.

The core itself may be of a uniform composition, or may have two or morelayers. The standards for both the diameter and weight for golf ballsare established by the United States Golf Association (U.S.G.A.).Although the compositions employed in the invention can be used in solidcore, two-piece and wound balls, solid and two-piece balls are preferredover wound balls due to their lower cost and superior performance. Theterm “solid cores” as used herein refers not only to one piece cores butalso to multi-layer cores.

The cores of the inventive golf balls typically have a coefficient ofrestitution of about 0.770 or more and a PGA compression of about 60 ormore, and more preferably about 80 or more. The core used in the golfball of the invention preferably is a solid. The cores generally have aweight of 25 to 40 grams and preferably 30 to 40 grams, although othersizes may be used if desired. When the golf ball of the invention has asolid core, this core can be compression molded from a slug of uncuredor lightly cured elastomer composition comprising a high cis contentpolybutadiene and a metal salt of an alpha, beta, ethylenicallyunsaturated carboxylic acid such as zinc mono- or diacrylate ormethacrylate. Any known elastomer composition known in the art may beused. To achieve higher coefficients of restitution and/or to increasehardness in the core, the manufacturer may include a small amount of ametal oxide such as zinc oxide. In addition, larger amounts of metaloxide than are needed to achieve the desired coefficient may be includedin order to increase the core weight so that the finished ball moreclosely approaches the U.S.G.A. upper weight limit of 1.620 ounces.Non-limiting examples of other materials which may be used in the corecomposition including compatible rubbers or ionomers, and low molecularweight fatty acids such as stearic acid. Free radical initiatorcatalysts such as one more peroxides are admixed with the corecomposition so that on the application of heat and pressure, a curing orcross-linking reaction takes place. Additional materials that may beadded to the core include, but are not limited to, organic and inorganicsulfur compounds; peptizers (such as pentachlorothiophenol or zincpentachlorothiophenol); high efficiency, heavy fillers (such astungsten, zinc, bismuth, and the like).

A thread wound core may comprise a liquid, solid, gel or multi-piececenter. The thread wound core is typically obtained by winding a threadof natural or synthetic rubber, or thermoplastic or thermosettingelastomer such as polyurethane, polyester, polyamide, etc. on a solid,liquid, gel or gas filled center to form a thread rubber layer that isthen covered with one or more mantle or cover layers. Additionally,prior to applying the cover layers, the thread wound core may be furthertreated or coated with an adhesive layer, protective layer, or anysubstance that may improve the integrity of the wound core duringapplication of the cover layers and ultimately in usage as a golf ball.Since the core material is not an integral part of the presentinvention, further detailed discussion concerning the specific types ofcore materials which may be utilized with the cover compositions of theinvention are not specifically set forth herein. Since the core materialis not an integral part of the present invention, a detailed discussionconcerning the specific types of core materials which may be utilizedwith the cover compositions of the invention are not specifically setforth herein.

Golf balls of the invention may be produced by forming covers whichinclude compositions of the invention around cores by conventionalmolding processes. The cover material is mixed in a rigorous mixingprocedure, preferably using a twin screw extruder or the like and anextrusion temperature of about 200□C. to 300□C. The cover compositionsmay be injection molded directly around the core while the core ispositioned in the center of a golf ball mold at a temperature of about350□F. up to about 500□F. In compression molding, the cover compositionis first injection molded at about 380□F. to about 450□F. to providesmooth surfaced hemispherical shells. The shells are then positionedaround the core in a dimpled golfball mold and compression molded atabout 230 to about 300□F. for about 2 minutes to about 10 minutes at apressure sufficient to retain the mold in a closed position. Thereafter,the mold is cooled at about 50□F. to about 70□F. for about 2 minutes toabout 10 minutes to fuse the shells together to form a unitary ball.After molding, the resulting golf balls may undergo various furtherprocessing steps such as buffing, painting and marking.

The present invention is further illustrated by the followingnon-limiting examples set forth below. In Table 3, which includes datafor the examples, the compositions are injection molded at about 500□F.around solid cores having a diameter of about 1.508″ to produceintermediate golfballs about 1.59″ in diameter. A cover layer is thenmolded over the intermediate golf ball. The properties for the ballslisted in the examples are measured according to the followingprocedures:

The resilience or coefficient of restitution (C.O.R.) of a golfball isthe constant “e,” which is the ratio of the relative velocity of anelastic sphere after direct impact to that before impact. As a result,the C.O.R. (“e”) can vary from 0 to 1, with 1 being equivalent to aperfectly or completely elastic collision and 0 being equivalent to aperfectly or completely inelastic collision.

C.O.R., along with additional factors such as club head speed, club headmass, ball weight, ball size and density, spin rate, angle of trajectoryand surface configuration (for example, dimple pattern and area ofdimple coverage) as well as environmental conditions (for example,temperature, moisture, atmospheric pressure, wind, etc.) generallydetermine the distance a ball will travel when hit. Along this line, thedistance a golfball will travel under controlled environmentalconditions is a function of the speed and mass of the club and size,density and resilience (C.O.R.) of the ball and other factors. Theinitial velocity of the club, the mass of the club and the angle of theball's departure are essentially provided by the golfer upon striking.Since club head, club head mass, the angle of trajectory andenvironmental conditions are not determinants controllable by golf ballproducers and the ball size and weight are set by the U.S.G.A., theseare not factors of concern among golf ball manufacturers. The factors ordeterminants of interest with respect to improved distance are generallythe coefficient of restitution (C.O.R.) and the surface configuration(dimple pattern, ratio of land area to dimple area, etc.) of the ball.

The C.O.R. in solid core balls is a function of the composition of themolded core and of the cover. The molded core and/or cover may becomprised of one or more layers such as in multi-layered balls. In ballscontaining a wound core (i.e., balls comprising a liquid or solidcenter, elastic windings, and a cover), the coefficient of restitutionis a function of not only the composition of the center and cover, butalso the composition and tension of the elastomeric windings. As in thesolid core balls, the center and cover of a wound core ball may alsoconsist of one or more layers.

The coefficient of restitution is the ratio of the outgoing velocity tothe incoming velocity. In the examples of this application, thecoefficient of restitution of a golf ball was measured by propelling aball horizontally at a speed of 125 5 feet per second (fps) andcorrected to 125 fps against a generally vertical, hard, flat steelplate and measuring the ball's incoming and outgoing velocityelectronically. Speeds were measured with a pair of Oehler Mark 55ballistic screens available from Oehler Research, Inc., P.O. Box 9135,Austin, Tex., which provide a timing pulse when an object passes throughthem. The screens were separated by 36″ and are located 25.25″ and61.25″ from the rebound wall. The ball speed was measured by timing thepulses from screen 1 to screen 2 on the way into the rebound wall (asthe average speed of the ball over 36″), and then the exit speed wastimed from screen 2 to screen 1 over the same distance. The rebound wallwas tilted 2 degrees from a vertical plane to allow the ball to reboundslightly downward in order to miss the edge of the cannon that fired it.The rebound wall is solid steel 2.5 inches thick and 24 inches square.

As indicated above, the incoming speed should be 125 5 fps but correctedto 125 fps. The correlation between C.O.R. and forward or incoming speedhas been studied and a correction has been made over the 5 fps range sothat the C.O.R is reported as if the ball had an incoming speed ofexactly 125.0 fps.

The coefficient of restitution must be carefully controlled in allcommercial golfballs if the ball is to be within the specificationsregulated by the United States Golf Association (U.S.G.A.). As mentionedto some degree above, the U.S.G.A. standards indicate that a“regulation” ball cannot have an initial velocity exceeding 255 feet persecond in an atmosphere of 75□F. when tested on a U.S.G.A. machine.Since the coefficient of restitution of a ball is related to the ball'sinitial velocity, it is highly desirable to produce a ball havingsufficiently high coefficient of restitution to closely approach theU.S.G.A. limit on initial velocity, while having an ample degree ofsoftness (i.e., hardness) to produce enhanced playability (i.e., spin,etc.).

The term “compression” utilized in the golfball trade generally definesthe overall deflection that a golf ball undergoes when subjected to acompressive load. For example, PGA compression indicates the amount ofchange in golf ball's shape upon striking. The development of solid coretechnology in two-piece balls has allowed for much more precise controlof compression in comparison to thread wound three-piece balls. This isbecause in the manufacture of solid core balls, the amount of deflectionor deformation is precisely controlled by the chemical formula used inmaking the cores. This differs from wound three-piece balls whereincompression is controlled in part by the winding process of the elasticthread. Thus, two-piece and multilayer solid core balls exhibit muchmore consistent compression readings than balls having wound cores suchas the thread wound three-piece balls.

In the past, PGA compression related to a scale of from 0 to 200 givento a golf ball. The lower the PGA compression value, the softer the feelof the ball upon striking. In practice, tournament quality balls havecompression ratings around 70 to 110, preferably around 80 to 100.

In determining PGA compression using the 0 to 200 scale, a standardforce is applied to the external surface of the ball. A ball whichexhibits no deflection (0.0 inches in deflection) is rated 200 and aball which deflects 2/10th of an inch (0.2 inches) is rated 0. Everychange of 0.001 of an inch in deflection represents a 1 point drop incompression. Consequently, a ball which deflects 0.1 inches (100×0.001inches) has a PGA compression value of 100 (for example, 200−100) and aball which deflects 0.110 inches (110×0.001 inches) has a PGAcompression of 90 (for example, 200−110).

In order to assist in the determination of compression, several deviceshave been employed by the industry. For example, PGA compression isdetermined by an apparatus fashioned in the form of a small press withan upper and lower anvil. The upper anvil is at rest against a 200-pounddie spring, and the lower anvil is movable through 0.300 inches by meansof a crank mechanism. In its open position the gap between the anvils is1.780 inches allowing a clearance of 0.100 inches for insertion of theball. As the lower anvil is raised by the crank, it compresses the ballagainst the upper anvil, such compression occurring during the last0.200 inches of stroke of the lower anvil, the ball then loading theupper anvil which in turn loads the spring. The equilibrium point of theupper anvil is measured by a dial micrometer if the anvil is deflectedby the ball more than 0.100 inches (less deflection is simply regardedas zero compression) and the reading on the micrometer dial is referredto as the compression of the ball. In practice, tournament quality ballshave compression ratings around 80 to 100 which means that the upperanvil was deflected a total of 0.120 to 0.100 inches.

An example to determine PGA compression can be shown by utilizing a golfball compression tester produced by Atti Engineering Corporation ofNewark, N.J. The value obtained by this tester relates to an arbitraryvalue expressed by a number which may range from 0 to 100, although avalue of 200 can be measured as indicated by two revolutions of the dialindicator on the apparatus. The value obtained defines the deflectionthat a golf ball undergoes when subjected to compressive loading. TheAtti test apparatus consists of a lower movable platform and an uppermovable spring-loaded anvil. The dial indicator is mounted such that itmeasures the upward movement of the springloaded anvil. The golf ball tobe tested is placed in the lower platform, which is then raised a fixeddistance. The upper portion of the golf ball comes in contact with andexerts a pressure on the springloaded anvil. Depending upon the distanceof the golf ball to be compressed, the upper anvil is forced upwardagainst the spring.

Several good alternative devices have also been employed to determinecompression. For example, Applicant also utilizes an Instron® 5544(manufactured by Instron Corporation, Canton, Mass.) to testcompression. Using the INSTRON® tester, compression is measured bydetermining the deflection caused by a 200 lb. load applied at the rateof 15 kips (thousand pounds of force per second).

Additional compression devices may also be utilized to monitor golf ballcompression so long as the correlation to PGA compression is known.These devices have been designed, such as a Whitney Tester, to correlateor correspond to PGA compression through a set relationship or formula.Another compression device which has been utilized in the past byApplicant is a modified Riehle Compression Machine originally producedby Riehle Bros. Testing Machine Company, Philadelphia, Pa. to evaluatecompression of the various components (i.e., cores, mantle cover balls,finished balls, etc.) of the golf balls. The Riehle compression devicedetermines deformation in thousandths of an inch under a load designedto emulate the 200 pound spring constant of the Atti or PGA compressiontesters. Using such a device, a Riehle compression of 61 corresponds toa deflection under load of 0.061 inches.

Additionally, an approximate relationship between Riehle compression andPGA compression exists for balls of the same size. It has beendetermined by Applicant that Riehle compression corresponds to PGAcompression by the general formula PGA compression=160−Riehlecompression. Consequently, 80 Riehle compression corresponds to 80 PGAcompression, 70 Riehle compression corresponds to 90 PGA compression,and 60 Riehle compression corresponds to 100 PGA compression. Forreporting purposes, Applicant's compression values were measured asRiehle compression and converted to PGA compression.

To measure the durability, finished golf balls were fired at 155ft/second against a 2″ thick steel plate. The durability specificationis no breaks below 20 blows.

EXAMPLES

Various mantle compositions were produced using a blend of ionomers andglass particles. The mantle compositions are shown in Table 1 below. Thecompositions were then injection molded around cores to yieldintermediate golf balls approximately 1.59 inches in diameter. The coresused in the examples were standard cores having a PGA compression ofabout 40 to 45 and a COR of about 0.76 to 0.77. A cover was then moldedon the intermediate balls as described above. Control balls having amantle layer of the same ionomer blend without glass particles were alsoproduced. The balls were then tested for various properties. The resultsare shown below in Table 3.

Examples 2 and 3 in Tables 1 and 3 illustrate golf balls formed withmantle layer compositions that include glass particles. Example 1 is thecontrol sample using the same ionomer blend except that here are noglass particles in the composition. TABLE 1 Component (phr) 1 2 3Surlyn ® 8140 50 50 50 Surlyn ® 9150 25 25 25 Surlyn ® 6120 25 25 25Microglas REV-4¹ —  5 — Aminosilane REF-015A glass — —  5 flake²¹Microglas REV-4 is a milled glass fiber having a fiber diameter ofabout 13 microns and a fiber length of about 70 microns, and REV-4 isuntreated.²Aminosilane REF-015A glass flake is an aminosilane treated microglasflake.

Other glass flakes and properties are shown below in Table 2. TABLE 2Type Non-Surface Treatment Surface Treatment Product Code REF-600REF-160 REF-015 REF-160T REF-160N Glass Composition E-Glass SpecificGravity 2.5 Thickness (μm) Average 5 ± 2 Particle Size >1700 μm 0 0 0 00 Distribution 1700˜300 80 or more 10 or less 12 or less 10 or less 10or less 300˜150 65 or more 65 or more 65 or more 150˜45 20 or less <45μm 25 or less 88 or more 25 or less 25 or less Loss on Ignition (%) —0.15 ± 0.10 0.15 ± 0.10 Surface Treatment Agent — EpoxysilaneAcrylsilane

TABLE 3 Example 1 2 3 Size (in) 1.684 1.685 1.684 Weight (grams) 45.7845.95 45.93 Riehle Compression 79 78 76 PGA Compression (calculated) 8182 84 COR 0.8031 0.8024 0.8040 High Speed Durability 119 122 137(average) First Break 42, 62, 75 89 81

As shown by the results in Table 3, the addition of glass particles tothe mantle composition of a golf ball results in a more durable golfball than the golf ball without glass particles in the mantle layer. Thegolf ball having a mantle layer comprising treated glass particlesproduced the most durable golf ball.

In any of the compositions employed in the invention, additionalmaterials may be added to these compositions employed to provide desiredproperties. These materials include, for example, dyes such asULTRAMARINE BLUE™ sold by Wittaker, Clark and Daniels of SouthPlainfield, N.J., titanium dioxide, UV absorbers and stabilizers.

In addition to the above noted materials, compatible additive materialsmay also be added to produce the cover compositions of the presentinvention. These additive materials include dyes (for example,ULTRAMARINE BLUE™ sold by Whitaker, Clark, and Daniels of SouthPlainsfield, N.J.), and pigments, i.e., white pigments such as titaniumdioxide (for example UNITANE™ 0-110) zinc oxide, and zinc sulfate, aswell as fluorescent pigments. As indicated in U.S. Pat. No. 4,884,814,the amount of pigment and/or dye used in conjunction with the polymericcover composition depends on the particular base resin mixture utilizedand the particular pigment and/or dye utilized. The concentration of thepigment in the polymeric cover composition can be from about 1% to about10% as based on the weight of the base resin mixture. A more preferredrange is from about 1% to about 5% as based on the weight of the baseresin mixture. The most preferred range is from about 1% to about 3% asbased on the weight of the base resin mixture. The most preferredpigment for use in accordance with this invention is titanium dioxide.

Moreover, since there are various hues of white, i.e., blue white,yellow white, etc., trace amounts of blue pigment may be added to thecover stock composition to impart a blue white appearance thereto.However, if different hues of the color white are desired, differentpigments can be added to the cover composition at the amounts necessaryto produce the color desired.

In addition, it is within the purview of this invention to add to thecover compositions of this invention compatible materials that do notaffect the basic novel characteristics of the composition of thisinvention. Among such materials are antioxidants (such as SANTONOX®,4,4′-di (1,1,3,3-tetramethylbutyl) diphenylamine sold under the tradedesignation “Octamine Antioxidant” by Naugatuck Division of US Rubber.Also useful is the hydroperoxide decomposer antidegradant tetrakis(2,4-ditertbutylphenyl)-4,4′-biphenylenediphosphonite sold under thetrade designation “SANDOSTAB P-EPQ” by Sandoz Colors & Chemicals Co.),antistatic agents, stabilizers and processing aids. The covercompositions of the present invention may also contain softening agents,such as plasticizers, etc., and reinforcing materials such as glassfibers and inorganic fillers, as long as the desired properties producedby the golf ball covers of the invention are not impaired.

Furthermore, optical brighteners, such as those disclosed in U.S. Pat.No. 4,679,795, herein incorporated by reference, may also be included inthe cover composition of the invention. Examples of suitable opticalbrighteners which can be used in accordance with this invention areUVITEX® OB as sold by the Ciba-Geigy Chemical Company, Ardsley, N.Y.UVITEX® OB is thought to be2,5-Bis(5-tert-butyl-2-benzoxazoly)thiophene. Examples of other opticalbrighteners suitable for use in accordance with this invention are asfollows: LEUCOPURE® EGM as sold by Sandoz, East Hanover, N.J. 07936.LEUCOPURE® EGM is thought to be 7-(2n-naphthol(1,2-d)-triazol2yl)-3-phenyl-coumarin. PHORWHITE® K-20G2 is sold by Mobay ChemicalCorporation, P.O. Box 385, Union Metro Park, Union, N.J. 07083, and isthought to be a pyrazoline derivative, EASTOBRITE® OB-1 as sold byEastman Chemical Products, Inc. Kingsport, Tenn., is thought to be4,4-Bis(-benzoxaczoly)stilbene. The above-mentioned UVITEX® andEASTOBRITE® OB-1 are preferred optical brighteners for use in accordancewith this invention.

Moreover, since many optical brighteners are colored, the percentage ofoptical brighteners utilized must not be excessive in order to preventthe optical brightener from functioning as a pigment or dye in its ownright.

The compositions employed in the invention may be prepared by anyconventional procedure that provides a substantially uniform admixtureof the components. Preferably drying and melt blending procedures andequipment are used. For example, in preparation of compositions whichemploy glass particles with one or more terpolymers and/or terpolymerionomers, the terpolymer and/or terpolymer ionomer can be dry mixed withthe glass particles, typically at room temperature, and the resultingmixture melt blended in any conventional type blending equipment heatedto about 200 to 250□C. The glass particles and the copolymer,terpolymer, terpolymer ionomer, and/or copolymer ionomer preferably aredried (either individually or together) before melt blending. Drying isdone in desiccated air at a temperature and for a time suitable toreduce the moisture content to a point which it will not have anyadverse effect on the subsequent use of the compositions or theproperties of the resulting product. If additives such as thoseidentified above have not previously been added to either the glassparticles, the copolymer or copolymer ionomer during processing of thoseindividual components (before they are admixed with each other), theadditives may be added during melt blending of those components. Theuniform admixture resulting from the melt blending procedure then may becommuted by chopping, pelletizing or grinding into granules, pellets,chips, flakes or powders suitable for subsequent use, for example,injection molding to provide a golf ball.

From the foregoing it is believed that those skilled in the pertinentart will recognize the meritorious advancement of this invention andwill readily understand that while the present invention has beendescribed in association with a preferred embodiment thereof, and otherembodiments illustrated in the accompanying drawings, numerous changes,modifications and substitutions of equivalents may be made thereinwithout departing from the spirit and scope of this invention which isintended to be unlimited by the foregoing except as may appear in thefollowing appended claims. Therefore, the embodiments of the inventionin which an exclusive property or privilege is claimed are defined inthe following appended claims.

1. A golf ball having improved durability, the golf ball comprising: acore; a mantle disposed on the core, the mantle comprising a compositioncomprising a mixture of glass particles and a polyurethane material; acover disposed on the core; and at least one cover layer disposed on themantle.
 2. The golf ball of claim 1, wherein the composition comprisesfrom about 0.5 to about 40 percent glass particles.
 3. The golf ball ofclaim 1, wherein the glass particles comprise surface treated glassparticles.
 4. The golfball of claim 3, wherein the cover comprises amixture of glass particles and a blend of ionomers.
 5. The golf ball ofclaim 1, wherein the glass particles comprise glass flakes.
 6. The golfball of claim 1, wherein the glass particles comprise glass fibers. 7.The golf ball of claim 1, wherein the glass particles are metal coated.8. A golf ball comprising: a core; a mantle comprising a polyurethanematerial and a plurality of glass particles in an amount of 0.5 to about40 weight percent of the composition; and a cover comprising an ionomermaterial.
 9. The golf ball according to claim 8 wherein the polyurethanematerial is a reaction injection molded polyurethane.
 10. The golfballaccording to claim 8 wherein the polyurethane material is a castpolyurethane.
 11. The golfball according to claim 8 wherein thepolyurethane material is an injection molded thermoplastic polyurethane.12. The golf ball according to claim 8 wherein the cover has thicknessranging from 0.010 inch to 0.040 inch.
 13. The golf ball according toclaim 8 wherein the mantle layer has a thickness ranging from 0.020 inchto 0.100 inch.